There are mainly two types of commercially available carburizing furnaces: ordinary carburizing furnaces and vacuum carburizing furnaces.
Ordinary carburizing furnaces use dimethylmethane (or acetone) as the carburizing atmosphere. Dimethylmethane (or acetone) decomposes at a high temperature to produce carbon atoms. Carbon atoms are free and cannot effectively reach the product surface, resulting in low carburizing speed and efficiency. To improve the carburizing speed and efficiency, some carrier gases (or enriched gases) such as methanol are usually added. The carrier gas (or enriched gas) carries the free carbon atoms in the furnace to the product surface, increasing the probability of contact between the product surface and carbon atoms, thereby improving the production efficiency.
Vacuum furnaces require high manufacturing costs and are unaffordable for many users. Vacuum carburizing furnaces have advantages of in high product quality and performance that ordinary carburizing furnaces cannot achieve, and are disadvantageous in high purchase costs, the need of professional heat treatment personnel and professional operators in use, and higher power consumption than ordinary carburizing furnaces.
The use of acetylene as the carburizing atmosphere is not applicable to ordinary carburizing furnaces because the carbon potential or decomposing furnace in the furnace cannot be actually measured. As acetylene does not compose at a high temperature, carbon atoms can be obtained through decomposition only by using a metal as the catalyst. Commercially available oxygen probes and carbon monoxide analyzers calculates the carbon potential with reference to the oxygen element in the furnace. The use of acetylene as the carburizing atmosphere is applicable to vacuum carburizing furnaces, because vacuum carburizing furnaces are controlled in a different manner Vacuum carburizing furnaces calculate the carbon-rich ability of the product surface by using a complex surface area calculation method, and control the acetylene intake volume by using pulses, so as to meet product carburizing requirements.